Once you summon Destiny HERO - Plasma, Alexis's monsters' effects are negated, meaning Destiny HERO - Plasma won't be destroyed or sent to the graveyard by the effects of her Cyber Angel Dakini or Cyber Gymnast.

If you don't have Desert Twister, add one more Secret Pass to Treasure. The first one will be negated by Alexis' Spell Shield Type-8, then the second one will be successfully activated.

Dark Paladin (7-8k)

Special summon Dark Paladin in DEF position as soon as possible using skills like Balance and Restart. Dark Paladin's effect can negate the activation of any spell card by discarding 1 hand, meaning Alexis' can't perform ritual summon. Note that Alexis uses the effect of Cyber Gymnast to destroy your Dark Paladin if it is ATK position.

Use King of the Swamp depending on what you need. You can send it to the Graveyard to get Polymerization or use it as a Fusion Substitue. It's recommended to have more copies of this card and replace other Fusion Substitute monsters.

If for some reason you don’t have two copies of Secret Pass for the dark paladin deck, Stop Defense is a pretty good substitute because you can use it to attack her Cyber Petit Angel. You’ll still get all the bonuses as if you attacked directly.